Active element pattern of multilayer and cavity-backed probe-fed microstrip patch arrays

A common way to characterize the scan performance and radiation characteristics of phased arrays is the active element pattern (AEP). In this work two procedures are proposed to compute the AEP in infinite planar arrays. The AEP is deduced from the Floquet´s harmonic representation of the electromagnetic field generated by the array. These techniques are applied to multilayer microstrip arrays represented by their general scattering matrix. The general scattering matrix of the stacked structure may be obtained from full wave numerical methods based on modular approaches. With these techniques, multilayer structures are analyzed in a more flexible and efficient way that with an integrated approach, since modifications on one layer do not require a whole re-computation. The proposed methods are applied to obtain the radiation characteristics of cavity backed and probe-fed microstrip patch arrays in single and stacked configurations.